It seems there's still a chance it might happen. It sounds like Burst has their system pretty much ready to go and Qora isn't far behind:
AT team will proceed as normally with the integration of AT, create a new wallet version, test it first on a testnet and then release it.
If in the meanwhile, full source code get released, AT team will probably revised their integration to fit to the latest code and Qora will decide if he is going to compile a new wallet version at that specific moment.
If the source code released after the wallet provided by AT team, then again, it will be merged.
Whether it's ready in time for them to win the bounty or not is another matter entirely. But mostly I just want to see this cross-chain system up and running. Even if it takes a bit more time to get it 100% right, the potential of this is genuinely exciting. It's times like this when I wish I had some coding knowledge to contribute and help speed things along, but I'll have to settle for cheering from the sidelines.